The invention is generally directed to printers and in particular to a serial dot printer with a character generator capable of generating characters of different pitches by generating different print timing signals.
Recently, high quality printing that approximates the quality of matrix font type printing has been achieved by increasing the number of dots used in a dot-matrix printer. As a result, a serial dot printer capable of dealing with various font types and a variety of character pitches is desired.
The print pitch of a serial dot printer is generally ten characters per inch. However, as the print quality improves, a printer capable of printing in a twelve and fifteen character per inch format, used in the matrix-font type printers is desired. One approach to this need is a printer system wherein a single printer has a number of character generators, each corresponding to a single print pitch rate. However, a printer of this type requires significant amounts of memory for each separate character generator, thereby increasing the cost of the printer.
Another approach to varying the print pitch between dots is to set the pitch of an encoder more finely than the actual print pitch and then frequency demultiplex the print timing signal to provide a print signal corresponding to a given print pitch. Still another approach has been to frequency divide the time interval between some pulses of the print timing system using a timer. Both of these approaches require a high resolution encoder which is a serious drawback in view of its high cost. In addition, accumulated errors increase the error in the location of the last print pitch position in the divided interval. Accordingly, there is a need for a printer having a print timing generator circuit which accurately generates print timing signals to generate characters at a variety of pitches without the need for high resolution encoders or large amounts of memory.